Technical Specifications
| Parameter Name | Value |
|---|---|
| Product Model | Allen‑Bradley 1769‑SM2 |
| Manufacturer | Rockwell Automation / Allen‑Bradley |
| Product Type | DSI/Modbus Network Communication Module |
| Series | 1769 Compact I/O |
| Number of Channels | 3 (CH1, CH2, CH3) |
| Supported Protocols | Drive Serial Interface (DSI), Modbus RTU Master |
| DSI Data Transfer Speed | 19.2 kbps |
| Modbus RTU Baud Rates | 300, 600, 1200, 2400, 4800, 9600, 19200, 38400 bps |
| Single Mode Drives Supported | Up to 3 (one per channel) |
| Multi-Drive Mode DSI Drives | Up to 15 (five per channel) |
| Modbus RTU Slave Devices | Up to 31 (when channel configured as Modbus Master) |
| Backplane Current Draw | 350 mA @ 5V DC; 0 mA @ 24V DC |
| Power Dissipation | 1.75 W typical |
| Power Supply Distance Rating | 8 modules maximum |
| Operating Temperature | -10°C to 50°C (14°F to 122°F) |
| Storage Temperature | -40°C to 85°C |
| Operating Vibration | 5g at 10‑500 Hz |
| Operating Shock | 30g at 11 ms |
| Dimensions (W x H x D) | 34 x 87 x 118 mm (1.34 x 3.43 x 4.65 in) |
| Weight | Approximately 0.2 kg (0.44 lbs) |
| Mounting | DIN Rail or Panel Mount |
| Wire Type | Copper‑90, 22‑14 AWG solid, 22‑16 AWG stranded |
| Maximum DSI Cable Distance | 10 m (32.8 ft) to PowerFlex 4‑Class drives |
| Maximum Modbus Cable Distance | 1219 m (4000 ft) on RS‑485 network |
| Status Indicators | Bi‑color (red/green) for module and each channel |
| Configuration Methods | RSLogix 500 v6.30+, RSLogix 5000 v10+, external HIM, DriveExplorer, DriveExecutive |
Main Features and Advantages
Flexible Communication Architecture Supporting DSI and Modbus RTU Master
The 1769‑SM2 delivers exceptional versatility with three independent channels that can be individually configured for Single drive mode, Multi‑Drive mode, or Modbus RTU Master operation. In Single mode, each of the three channels connects directly to one PowerFlex 4‑Class drive using a dedicated RJ45 connection, providing a straightforward one‑to‑one interface ideal for applications with up to three drives. In Multi‑Drive mode, each channel supports daisy‑chained connections to up to five drives, enabling a single 1769‑SM2 to control up to 15 PowerFlex drives across a single RS‑485 network. Furthermore, any channel operating in Multi‑Drive mode can be configured as a Modbus RTU Master, extending connectivity to a maximum of 31 Modbus slave devices such as PowerFlex 7‑Class drives with 20‑COMM‑H adapters—a capability that consolidates drive communication without requiring separate Modbus gateway hardware.
Parameter‑Configurable I/O with Explicit Messaging Support
The 1769‑SM2 provides comprehensive I/O configurability, allowing users to define Logic Command/Reference and Logic Status/Feedback for each connected drive through simple parameter settings. This configuration can be performed through RSLogix 500 (v6.30 or higher) for MicroLogix 1500 systems, or RSLogix 5000 (v10 or higher) for CompactLogix controllers, providing seamless integration with the Rockwell Automation software ecosystem. The 1769‑SM2 supports explicit messaging for parameter reads and writes, enabling advanced application features such as dynamic drive parameter adjustment during operation—a critical capability for applications requiring real‑time performance optimization. Additionally, user‑defined fault actions allow the 1769‑SM2 to determine how the module and connected drives respond when the controller enters idle mode, preventing unexpected drive behavior during program downloads or processor faults.
Robust Diagnostics and Ease of Installation
The 1769‑SM2 features bi‑color status indicators on the front panel that provide immediate visual confirmation of module health and channel communication status. A green MODULE status indicates normal operation and established communication with the controller, while individual channel LEDs report the status of each DSI connection, enabling rapid troubleshooting without requiring software tools. The module is designed for straightforward installation within the 1769 Compact I/O system, fitting into a single slot and receiving power directly from the backplane—eliminating the need for separate power wiring. The 1769‑SM2 supports both panel and DIN rail mounting, with removable terminal blocks and RJ45 connectors simplifying field wiring and maintenance.
Application Fields
Variable Frequency Drive Control and Monitoring
The 1769‑SM2 is primarily deployed in applications requiring centralized control and monitoring of multiple PowerFlex drives from a CompactLogix or MicroLogix 1500 controller. In a typical conveyor system installation, a single 1769‑SM2 can manage up to 15 PowerFlex 4‑Class drives across three separate network channels, each channel controlling a different zone or section of the conveyor line. This architecture significantly reduces wiring complexity compared to traditional hardwired control, while the module’s parameter‑configurable I/O enables each drive to receive independent speed references, start/stop commands, and fault reset signals—providing granular control of material handling operations without requiring a separate network adapter per drive.
HVAC and Building Automation Systems
In commercial and industrial HVAC applications, the 1769‑SM2 provides an efficient interface between the building automation controller and multiple variable frequency drives powering air handling units, cooling towers, and chilled water pumps. The module’s Multi‑Drive mode is particularly advantageous in large HVAC installations where numerous drives are distributed across a facility; a single 1769‑SM2 can communicate with groups of drives over long‑run RS‑485 wiring while providing real‑time status feedback, including operating speed, current draw, and fault conditions. The Modbus RTU Master capability allows the 1769‑SM2 to interface with PowerFlex 7‑Class drives and other Modbus‑compatible devices, integrating both DSI‑native and Modbus devices within the same communication network.
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